Rock varnish dating between dating difference relationship
Thus a Chlorine-36 date may reflect either recent exposure of a surface due to processes such as frost shattering, or an original exposure date. Professor Bowen and colleagues have obtained a date of c.
This difficulty of interpretation is why Chlorine-36 dating is normally done on boulders or lava surfaces whose erosional history is known (e.g. 14,000 years exposure time for the fragment from Stonehenge.
During the Holocene interglacial time, however, 0.5–1 ky long brief episodes of fan deposition may be linked to short periods of relatively wet climate.
C method, indicates that some petroglyphs (rock art) at El-Hosh in Upper Egypt pre-date the early 7th millennium BP (mid 6th millennium cal BC), making it the oldest graphic activity recorded in the Nile Valley.
Varnish microlamination (VML) dating is a correlative age determination technique that can be used to date and correlate various geomorphic features in deserts.
In this study, we establish a generalized late Quaternary (i.e., 0–300 ka) varnish layering sequence for the drylands of western USA and tentatively correlate it with the SPECMAP oxygen isotope record.
) that was published in 1994 --- around 14,000 years BP. ========================= Chlorine-36 dating has important potential for archaeology, but recent Chlorine-36 dates on `bluestones' of Stonehenge have been misinterpreted. 400,000 years or earlier, when the fragment and outcrop were apparently still buried or covered, and not exposed for ice transport (Bowen 1994: 211; Hawkes 1994; British Archaeology News 1995).
The rock type of this fragment is unknown, and the sample now completely destroyed (Professor D. Bowen, in discussion at the meeting of the Lithic Studies Group, Cardiff, 28 January 1995), so it may be nothing to do with the bluestone monoliths.
Carn Menyn loses material from outcrop surfaces every year through frost shattering. A date of 5000 years could represent a preserved quarried surface (in which case it might be expected to show quarry marks), or it could be a frost-shattered surface. Stonehenge dating dispels icesheet theory, The Times: .
The article in British Archaeology suggests that dating a monolith surface of a bluestone at Stonehenge will resolve the problem. At least some of the bluestones were dressed and the argument continues about which, and how many were altered in this way. A dressed or damaged bluestone will give a Chlorine-36 date reflecting total exposure time - for example, about 4000 years if it is dressed but not subsequently damaged.
A variety of older dates could be obtained, depending on whether the bluestone was removed from Wales by a glacier as an erratic, buried for part or all of its glacial transport, or broken up by erosional processes in post-glacial times.